Insulating material of metal film bonded to non-woven glass fabric with ethylene/vinyl acetate copolymer adhesive

ABSTRACT

A laminated insulating material comprised of a metal foil sheet bonded to a non-woven glass fiber paper-like sheet by a latex acrylic adhesive.

This application is a division of application, Ser. No. 032,286 filedApr. 23, 1979, now U.S. Pat. No. 4,242,165, for Insulating Material andProcess for Manufacturing Same by Julius Shaw.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The product and process disclosed herein reside in the field ofinsulating materials and processes for making same and more particularlyrelate to an improved, relatively thin material utilized for insulationespecially in construction of electrical and/or heat-producing devices.

Materials for heat insulation in the construction of electrical and/orheat-producing devices such as light fixtures have long been utilized.In the past they have often taken the form of non-combustible materialsbonded to a backing, for example, asbestos fibers bonded to a metalfoil. The advantage of asbestos is that it has high temperature andflame resistance. Unfortunately asbestos has been found to be acarcinogen and is no longer a favored material for the manufacture ofsuch relatively thin insulating materials. Currently in use is ceramicpaper, but this material is extremely expensive and its widespread useis thereby limited.

2. Summary

It is an object of the present invention to provide an improved,relatively thin material in laminate form and a process for producingsame that can be utilized for insulating purposes and have light andheat reflecting properties.

It is a further object that the material of the present invention can besupplied in sheets, rolls or pieces cut to a desired shape.

It is another object of this invention to provide a fire and heatresistant material which will neither rot nor corrode, will haveflexibility to conform to the areas of its use and yet not have anyharmful characteristics.

It is a further object of the present invention to provide a low-densityinsulating material that is both dimensionally stable and lightweightand which can be utilized in a variety of areas such as electriclighting fixtures, electronic equipment, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a segment of the laminate of thisinvention.

FIG. 2 is a perspective view of the apparatus for manufacturing thelaminate of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The insulating material of this invention seen in FIG. 1 is a laminatecomprised of a metal foil 10 bonded to a non-woven glass fiberpaper-like material 12. The metal foil of this invention which can bealuminum foil or other equivalent metal foils, can be provided in athickness of 0.0007 in. to 0.001 in. The non-woven glass fiberpaper-like material can be provided in the range of 0.015 in. to 0.070in. The laminate of this invention has a wide range of uses utilizingsuch glass fiber paper-like material in a thickness of 0.015 in. whichis bonded to a 0.001 in. aluminum foil. A plasticized ethylene vinylacetate co-polymer emulsion or equivalent latex acrylic is used as anadhesive to bind the metal foil to the glass fiber paper-like material.One such adhesive is supplied by American Finish and Chemical Co. ofChelsea, Mass. and has a product number of SRD870. Equivalent adhesivematerials can include vinyl acetate homo-polymers which make use ofplasticizers to soften the film formed to improve flexibility of thelaminate such as phthalate esters, phthalyl glycolates or phosphateesters. In the process of manufacturing the insulating laminate of thisinvention, one can utilize rolls of metal foil such as aluminum foil androlls of a non-woven glass fiber paper-like material, the rolls being ofsubstantially equal width. In FIG. 2 aluminum foil web 20 is passed overa resilient rubber roller 22 above which is disposed a knife 24.Positioned before knife 24 is adhesive 25 resting upon foil web 20 whichpasses under knife 24. Knife 24 is disposed above roller 22 and web 20approximately 3.5 mils so as to allow some adhesive 25 to be carried onweb 20 under knife 24. Rubber roller 22 helps to allow for anyunevenness in the web to protect knife 24. The adhesive can bemechanically applied before the knife or can be ladled into position. Asthe web of foil passes thereunder, the adhesive forms a film thereon. Ithas been found that a knife height of 3.5 mm. cited above avoids theformation of any bubbles or bare spots upon the foil web and providesfor an even dispersement thereon of the adhesive. If too much adhesiveis used, it is wasteful and also can affect the flexibility of thelaminate. Disposed above the foil web is a roll containing the glassfiber paper-like web in the thickness and dimensions cited above. Theglass fiber paper-like web is passed under an expander roller 28 toremove wrinkles and then under a marriage roller 30 which it mates withfoil web 20 and the laminate thus formed passes over an idler roller 32.The glass fiber paper-like web 26 and foil web 20 are further compressedtogether with the adhesive forming a bond therebetween, the adhesivebeing forced from the bottom web into the interstices of the glass fiberpaper-like material. The laminate is passed over a series, preferablysix, of can rollers 34, each composed of stainless steel heated usuallyby steam to a temperature range of 225° F.-240° F. which heat treatmentcures the adhesive for a more permanent bond. It has been found that ifthe laminate dries without sufficient heat, over a period of time thepolymers in the adhesive will not properly bond and the laminate willseparate. The laminate upon exiting from the last can roller 34 is thenrolled upon a take-up reel 36. The glass fiber paper-like material maybe somewhat thicker before lamination as there is a certain amount ofcompression which takes place in the process of this invention. Thelaminate material after curing can then be utilized.

The laminated rolls are usually spread out into sheets for largeapplications or can be die cut into discrete shapes for particular usesin electrical apparatuses. Underwriters Laboratory has approved the useof the laminate of this invention insofar as there is no danger of fire.It has been found that the laminate of this invention can be usedsuccessfully with temperatures up to 600° F. and the metal foil providesgood reflectance of both light and infrared rays in applications wheresuch properties are desirable.

Although the present invention has been described with reference toparticular embodiments, it will be apparent to those skilled in the artthat variations and modifications can be substituted therefor withoutdeparting from the principles and spirit of the invention.

I claim:
 1. A laminate for use in insulation of electrical apparatusescomprising:a metal foil sheet such as aluminum foil, having a thicknessof between 0.0007 in. and 0.001 in.; a non-woven glass fiber paper-likesheet having a thickness of between 0.015 in. and 0.070 in.; and aplasticized ethylene vinyl acetate co-polymer emulsion-type adhesivebonding said metal foil sheet to said non-woven glass fiber paper-likesheet.